Endometriosis and polyendocrine metabolic ovarian syndrome (PMOS) are two common and distressing conditions that reduce quality of life. While usually considered separately in research and clinical settings, co-occurrence does occur. One recent study suggested that one in 50 women have both endometriosis and PMOS1. Recent GWAS-based studies have identified risk loci shared between endometriosis and PMOS2 suggesting a complex interaction between the two conditions. Data from our Aotearoa-based online survey are consistent with a complex interaction between the two conditions at a clinical, biological and psychosocial level with co-occurrence exacerbating symptoms and complicating diagnosis. In contrast, an evolutionary hypothesis suggests that the risk factors for endometriosis and PMOS are diametrically opposed, being modulated by low versus high prenatal androgen exposure, respectively3. We postulate that improved understanding of the intersection of endometriosis and PMOS – the symptom profiles, disease presentation and phenotype, and clinical experience – may inform our understanding of both conditions and their heterogeneity. Current data and future plans considering the interaction of endometriosis and PMOS will be discussed.